Didn't you or someone else make this exact same thread like a year ago?
Anyway, the reason is obvious, porting from PS4 to X1 is simple, they're roughly the same architectures even, PS4 is just a bit faster.
I could be wrong but just because its Disney doesn't mean its gaurunteed to sell on a Nintendo platform either. I believe Square-Enix was kinda let down by Kingdom Hearts' sales on the 3DS. I think they were expecting more.